Why is there still formaldehyde in a newly renovated house one year later? Beware of these "hidden corners"

After finishing the renovation of their new house, many families will choose to leave the new house vacant and ventilate it for several months to remove the odor in the new house. However, there is a problem that bothers many families, that is, how many months after the renovation the new house needs to be ventilated before it is safe to move in?

Image source: soogif

Some families ventilated their rooms for a month before moving in, and the air in their rooms is fresh and odor-free. Some families waited for half a year or even a year before moving in, but could still smell a faint pungent odor in the room.

What exactly are these irritating odors? Where do they come from in the room? How can we effectively remove them?

01

From formaldehyde to volatility

Large family of organic pollutants

When decorating a new house, the thing people mention most is formaldehyde.

Formaldehyde is often used in many fields as a raw material for the production of adhesives, printing and dyeing auxiliaries, pesticides, and engineering plastics. It has strong toxicity and reducing properties and is a Class I carcinogen defined by the World Health Organization.

In addition, formaldehyde is a type of volatile organic pollutant with a boiling point of -19.5°C. Formaldehyde is highly volatile at room temperature and can enter the human body through the respiratory tract and skin, seriously endangering human health.

Image source: Photo Network

In addition to formaldehyde, there are many other types of volatile organic pollutants (TVOC), including hydrocarbons, aldehydes, ketones, alcohols, ethers, etc. Typical indoor volatile organic pollutants include benzene, toluene, ethylbenzene, xylene, formaldehyde, acetaldehyde, dichloromethane, trichloromethane, and benzopyrene.

TVOC, formaldehyde, toluene, xylene, benzene concentrations and oxygen consumption are the main indicators for indoor air quality testing. Friends who have done relevant tests must be familiar with them.

Generally speaking, if there is a pungent smell in a new house and symptoms such as coughing, dizziness, nausea and skin allergies occur after staying there for a long time, it is most likely caused by volatile organic pollutants.

Hazards of Volatile Organic Pollutants Source: CertifiedIAQPros

02

Volatile organic pollutants

How badly has it hurt you?

Most volatile organic pollutants are toxic, and some have triple effects (carcinogenic, teratogenic, and mutagenic).

In terms of short-term effects , volatile organic pollutants can irritate the eyes, skin and throat, causing coughing, skin allergies, dizziness, and even lung and bronchial inflammation.

In terms of long-term effects , it can cause damage to internal organs (lungs, liver, heart), skin, blood system, central nervous system, and reproductive system, and in severe cases can cause cancer.

Taking formaldehyde as an example, the steric hindrance of formaldehyde molecules is small, and the carbonyl functional group they carry is relatively active. It can not only induce DNA damage through DNA adduction and cross-linking, but also cause inactivation or dysfunction of repair enzymes or proteins through adduction and cross-linking, form methylene bridges between proteins and DNA molecules, lead to gene mutations, etc., and then induce the occurrence of tumors.

There are many cases of pregnant women and children suffering from leukemia due to formaldehyde. Fetuses and children are in a period of vigorous development, and cell growth and development are very active. Long-term exposure to formaldehyde environment is prone to produce cancer cells during DNA replication or DNA-controlled protein synthesis. From this perspective, formaldehyde is more harmful to pregnant women and children.

Formaldehyde genotoxicity

Image source: Frontiers in Microbiology

DNA cross-linking and addition process Source: Cell

03

There are dangers in hidden corners

After a new house is renovated, where do volatile organic pollutants come from?

Indoor volatile organic pollutants are mainly found in various solvents, adhesives and other chemical products. We can simply divide the sources of these indoor pollutants into three categories: indoor decoration materials, indoor furniture and building materials.

Paints, coatings, adhesives, wallpapers and other interior decoration materials are likely to contain excessive amounts of formaldehyde and benzene; volatile organic pollutants in building materials come from artificial boards, foam insulation materials and plastic sheets; and among indoor furniture, the most serious release of pollutants comes from wooden furniture itself and its adhesives and coatings, including wooden bookcases, cabinets, wardrobes, tables and chairs.

Therefore, generally speaking, bedrooms and study rooms are the areas where pollutants are most likely to accumulate after decoration , and they require everyone's special attention.

Source of indoor volatile organic pollutants release: Board Network

04

Get rid of the "poison gas" and relax your family

How to reduce indoor volatile organic compounds?

The first is ventilation, which is economical, effective, simple and easy to operate. Without considering the time cost, natural ventilation can solve most of the VOC pollution.

However, the release cycle of some pollutants, such as formaldehyde, can be more than three years . It is obviously unrealistic to leave a house idle for a long time . Therefore, a combination of natural ventilation and forced ventilation can be adopted to speed up ventilation efficiency through fans or fresh air systems.

Image source: Photo Network

It should be noted that the higher the indoor temperature, the greater the amount of pollutants volatilized, and the better the effect of natural ventilation and forced ventilation. From a seasonal perspective, ventilation is better in summer than in winter, and better during the day than at night. Of course, you can also turn on the heating equipment and close the doors and windows to increase the indoor temperature, and after a period of time, combine forced ventilation and natural ventilation to quickly dilute indoor pollutants.

The second is to fundamentally reduce the source of pollutants to prevent them from entering the environment, or use isolation equipment to cut off the transmission pathways of pollutants into the room during the transmission process.

When decorating the walls of living rooms and bedrooms, try to minimize the use of artificial boards for wall panels; try to minimize the use of decorative boards such as particleboard, hardwood plywood, medium-strength density board, etc. for laying floors. When it is unavoidable to use artificial boards, they can be harmlessly treated, such as applying paint on the saw cuts to make them highly solidified; reduce the use of oil-based paints, and try to use environmentally friendly paints such as water-based paints while ensuring color and economy; use environmentally friendly furniture, especially wooden furniture, and it is recommended to use furniture made of E0 or E1 environmentally friendly standard materials.

If it is not possible to reduce pollutants at the source and you need to move in as soon as possible, you need to use air purification technology to quickly reduce pollutants. The dedicated purification instrument collects and purifies the air in the room and then returns the gas to the room or directly discharges it to the outside.

Purifiers generally include electrostatic, adsorption, nano-photocatalysis or a combination of several types, among which adsorption is the most commonly used, mainly using activated carbon as the adsorption material. However, it should be mentioned that the use of purifiers should be appropriate, and the adsorption/catalytic materials should be replaced in time to avoid secondary pollution (ozone release and pollutant desorption).

There are many spray purifiers on the market that use photocatalysts or biological enzymes to reduce indoor pollutants. They can effectively degrade pollutants in the short term, but the release cycle of volatile organic pollutants such as formaldehyde in decoration materials is usually long, and in the long run they can only play an auxiliary role.

Finally, indoor plants are used for purification. Green plants are a beautiful and practical way to purify indoor volatile organic pollutants. Related studies have shown that plants that can better absorb indoor pollutants such as formaldehyde and benzene include spider plants, tiger skin plants, aloe vera, green radish, tiger tail plants, weeping figs, and peacock arrowroots. However, it should be remembered that this method can only play an auxiliary role and cannot replace any of the above methods.

Chlorophytum source: Photo Network

In addition, there are several points we need to pay attention to.

The first is the pollutant superposition effect . Although individual furniture and decoration materials of a certain area meet the pollutant emission standards, the accumulation of quantity and area will lead to a great increase in the release of volatile organic pollutants. So don’t think that the pollutant concentration can meet the standards by using environmentally friendly furniture and decoration materials.

The second is that the use of heating equipment will cause a large amount of volatile organic pollutants to be released , so you must pay attention to ventilation during the winter heating period after the new house is renovated.

Third, in addition to volatile organic pollutants, particulate pollutants and other gaseous pollutants are also important causes of indoor pollution , especially ammonia and the radioactive element radon.

References:

[1] Zhao Hui, Wang Di, Yu Ping, Wu Sisi, Wang Ying, Wang Zhixia. Early biological effects of formaldehyde toxicity in building environments[J]. Building Science, 2011, 27(11): 64-67.

[2] Sun Ting, Liu Fengjuan. Research progress on indoor formaldehyde pollution control methods[J]. Environmental Ecology, 2021, 3(08): 91-95.

[3] Lan Meichen, Hou Chi. Hazards and prevention of indoor volatile organic pollutants[J]. Henan Science and Technology, 2022, 41(05): 120-123.

[4] Nathan H. Chen, Karrera Y. Djoko, Frédéric J. Veyrier, Alastair G. McEwan, Formaldehyde Stress Responses in Bacterial Pathogens, Frontiers in Microbiology, 2016, 7 https://doi.org/10.3389/fmicb.2016.00257.

Author: Environmental Bacteria

PhD in Environmental Science and Engineering, Hunan University

Editor: Guru